Programmable processor-controlled data terminal equipment (DTE) such as work stations, data terminals, and personal computers are increasingly common in today's society.
It is known to program such a DTE to perform a desired function or application such as, for example, word processing or data terminal emulation. This is accomplished by programming the DTE's processor with a suitable application program that has been customized for the desired function.
It is also known to program such a DTE to communicate with another remote DTE or other source. This is accomplished by coupling the DTE's processor to a data communications equipment (DCE) or modem via a suitable DTE-DCE interface such as an RS-232 type. The modem, in turn, is coupled to a telephone line or other transmission facility. The processor may then be programmed to exchange information with the modem which, in turn, converts the information into signals suitable for transmission to the remote source via the telephone line.
A wide variety of modems are available to support such DTE-modem arrangements. In the prior art, these modems have either been stand-alone units external to the DTE or else customized plug-in units that are mounted internal to the DTE.
The problem with this DTE-modem arrangement is it is processor-redundant. This is because the modem itself typically contains at least one onboard processor to implement various modem functions such as modulation, demodulation, interfacing with the DTE, and other control functions. As a result, the total cost of the DTE-modem arrangement includes the cost of both the DTE's processor as well as the modem's processor. In the long run, this arrangement is inefficient, since it forces the DTE-modem user ultimately to pay for two (or more) processors when, with appropriate software and hardware, the single processor of the DTE could perform the same function.
Therefore, it would be desirable to provide an improved DTE-modem arrangement. Further, it would be particularly desirable to arrange the DTE processor to both execute an application program and implement a modem, thereby eliminating the need for the stand-alone modem.